Device for measuring a b-component of a magnetic field, a magnetic field sensor and an ammeter

ABSTRACT

Proposed is a device ( 10 ), a magnetic-field sensor, and an ammeter; a field distribution ( 50 ) of a first electric field being provided in a region ( 20 ) in such a manner, that the magnitude of the x component of the first electric field increases in the x direction.

[0001] The present invention relates to a device for measuring a Bcomponent of a magnetic field according to definition of the species inclaim 1, as well as to a magnetic-field sensor and an ammeter accordingto the species defined in the further, dependent claims.

BACKGROUND INFORMATION

[0002] The present state of technological development allows magneticfields, e.g. of current conductors, to be measured by magnetic-fieldsensors, e.g. Hall-effect sensors. According to the related art, fluxconcentrators are used in order to be able to measure very smallmagnetic fields, as well, with the aid of such magnetic-field sensors.Such flux concentrators are essentially made up of high-permeabilitymaterials, which are positioned with respect to the magnetic field to bemeasured, in such a manner, that an increase in the measuringsensitivity results from the combination of a magnetic-field sensor anda flux concentrator. A disadvantage of flux concentrators is that theyshow saturation effects and signs of hysteresis. In addition, the spacerequirements and the costs of flux concentrators are disadvantageous.

SUMMARY OF THE INVENTION

[0003] For the reasons mentioned above, is useful to increase thesensitivity of magnetic-field sensors as much as possible, in order toobtain, in this manner, a greater dynamic scope or greater dynamicranges of measurable magnetic fields.

[0004] Modern technologies reveal more and more fields of applicationfor very sensitive magnetic-field measuring methods. Particularly in theautomobile sector, the number of potential areas of use formagnetic-field sensors is growing; in particular, magnetic fieldmeasurement can be used, inter alia, for the non-contact, low-loss, andisolated measurement of currents. Examples include the determination ofelectrical operating parameters of generators and electrical drive unitsor the highly sensitive monitoring of the state of a battery inso-called energy-battery management. In general, currents from themilliampere range to the kiloampere range must be measured, whichrequires a measuring range of approximately five to six orders ofmagnitude.

[0005] The device of the present invention according to the speciesdefined in claim 1, and according to the dependent claims, has theadvantage that the sensitivity of the magnetic field measurement isincreased in comparison with known sensors, in particular Hall-effectsensors. Nevertheless, the present invention provides for the linearrelationship between the measuring signal of the device according to thepresent invention and the magnetic field to be measured to bemaintained. The increase in the sensitivity of the sensor allowsadditional, flux-concentrating measures, such as magnetic circuits (fluxguides), to be eliminated in many applications, so that a device of thepresent invention for measuring a magnetic field may be constructed in aconsiderably simpler and more cost-effective manner, and with lessexpenditure for assembly, than a customary device of this kind. Afurther advantage of the present invention is that the deflection angle,which the charge carriers experience due to the magnetic field to bemeasured, is greater than in the case of customary magnetic-fieldsensors operating according to the Hall principal. By this means, thesensitivity is increased in comparison with the standard Hall-effectsensor by increasing the magnetic-field effect on the flight path ofcharge carriers. Furthermore, it is advantageous that the increase inthe sensitivity of the magnetic-field sensor according to the presentinvention is solely achieved by the design of the device for magneticfield measurement. By this means, a highly sensitive component iscreated, which may be manufactured simply and cost-effectively, usingstandard process technique, such as bipolar, BCD, or CMOS processtechnique. In addition, it is particularly advantageous that, accordingto the present invention, there is a linear relationship between themagnetic field to be measured and the measuring signal generated by thedevice.

[0006] Advantageous further refinements and improvements of the deviceaccording to the present invention are specified in the dependentclaims.

[0007] In particular, is advantageous that an electric field, by whichthe charge carriers are introduced into the area, is provided between afirst terminal and a second terminal. By this means, the introduction ofthe charge carriers and their drift through the area are realized in asimple and reliable manner.

[0008] Furthermore, it is advantageous that, in order to produce thefield distribution, either a lateral electric field or a lateralparticle gradient or a lateral diffusion profile or the modulation ofthe band edges or the modulation of the Fermi levels in local space,e.g. using built-in potential barriers in nipi structures, is provided.In this connection, a structure, in which n-doped, intrinsic, p-doped,and intrinsic semiconductor layers are alternatingly provided, isunderstood as an nipi structure in a semiconductor. The layer sequencen-i-p-i may also be continued periodically: n-i-p-i-n-i-p-i-n-i-p-i . .. . The variation between n and p layers produces a potential-barrierstructure, as one knows from a simple p-n junction. A suitablydimensioned layer sequence of p-n-p-n-p-n- . . . not having anintrinsic, intermediate layer may also be suitable for producing thedesired potential barrier. In this manner, the device of the presentinvention may be produced by different manufacturing methods, so that ineach instance, the most cost-effective or optimal method may beconsidered for use.

BRIEF DESCRIPTION OF THE DRAWING

[0009] Exemplary embodiments of the present invention are shown in thedrawing and explained in greater detail in the following description.The figures show:

[0010]FIG. 1 the schematic representation of the standard Hallprinciple;

[0011]FIG. 2 a model representation of the deflection of electrons inthe magnetic field;

[0012]FIG. 3 a diagrammatic sketch of a first specific embodiment of thedevice according to the present invention;

[0013]FIG. 4 a diagrammatic sketch of a second specific embodiment ofthe device according to the present invention;

[0014]FIG. 5 a diagrammatic sketch of a third specific embodiment of thedevice according to the present invention; and

[0015]FIG. 6 a diagrammatic sketch of a fourth specific embodiment ofthe device according to the present invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0016] The functioning principle of a standard Hall-effect sensor 10 isschematically represented in FIG. 1. Hall-effect sensor 10 includes aregion 20, which is normally provided in a semiconductor substrate. Inaddition, Hall-effect sensor 10 includes a first terminal 21 and asecond terminal 22. Provided between first terminal 21 and secondterminal 22 is an electric field not shown, through which a chargecarrier 30 that is denoted in the figure by a minus sign, as a negativecharge carrier 30, is moved from first terminal 21, through region 20,to second terminal 22. Accordingly, first terminal 21 is at a negativepotential and denoted by a minus sign, while second terminal 22 isindicated by a positive sign and is at a positive potential. The voltageapplied between first terminal 21 and second terminal 22 brings chargecarrier 30 from first terminal 21 into region 20; this occurring alongan introduction direction, which is designated in the figure to be inthe vertical direction from the top to the bottom, between firstterminal 21 and second terminal 22. By this means, charge carrier 30 ismoved between first terminal 21 and second terminal 22, along a firstmovement direction 31 indicated by an arrow 31 pointing vertically fromtop to bottom.

[0017] For the case in which a magnetic field's magnetic-field componentBZ denoted by reference numeral 12 is provided in a directionperpendicular to the introduction direction and accordinglyperpendicular to first movement direction 31 of charge carrier 30,whereby magnetic-field component 12 is also denoted as B component 12and points into the plane of the drawing in FIG. 1, charge carrier 30 isdeflected by the Lorenz force in region 20. This means that chargecarrier 30 no longer moves according to the standard Hall principle,along first movement direction 31, but rather according to a secondmovement direction 32, which is represented in FIG. 1 by an arrow thatis positioned at an angle to first movement direction 31 and denoted byreference numeral 32. The angle between first movement direction 31 andsecond movement direction 32 of charge carrier 30, which is alsoreferred to in the following as angle α, is a function of the intensityof the magnetic-field component or B component 12 in the z direction,i.e. into the plane of the paper in FIG. 1. In reality, the Lorenz forceapplies a force to charge carrier 30 in such manner, that a curved,circular path (cycloids) is formed from an originally straight flightpath. However, the curved, circular path is not detectable, since, ineach case, charge carrier 30 can only fly ballistically, i.e.undisturbed, in real region 20 for approximately 100 fs before collidingwith the atoms of the crystal lattice. Therefore, the angular changeattainable in a cycloid is extremely small. The collision with thecrystal lattice causes charge carrier 30 to lose its previousdirectional information and its velocity, so that it must then bere-accelerated and traces a further cycloidal path from the point of thecollision. The trajectory of charge carrier 30 along second movementdirection 32 is indicated by reference numeral 33, using severalcycloids positioned one behind the other.

[0018] To better illustrate the directions used in FIG. 1 and in thesubsequent figures, a coordinate system 14 having an x axis, a y axis,and a z axis that are each provided with arrows is represented in theleft part of FIG. 1, the arrows starting out from a common origin.Coordinate system 14 is sketched in light perspective, the z directionpointing into the plane of the drawing, the x axis corresponding to thehorizontal, and the y axis corresponding to the vertical.

[0019] As reference numerals 32 and 33 indicate, the entire flight pathof a charge carrier 30 in region 20 is made up of curved cycloidal pathparts, which are each traced one after another for approximately 100 fs.Therefore, average, total deflection angle α is identical to thedeflection angle of a single cycloidal path. The angular change of theflight path produced in this manner is extremely small, typically lessthan 1°. Correspondingly small are the macroscopically attainableeffects, i.e. the sensitivity of the magnetic field measurement of Bcomponent 12 in a Hall-effect element, in which the current flowing infirst movement direction 31 is laterally deflected by B component 12 tosecond movement direction 32. In the case of the proposed device,deflection angle 34 is increased according to the present invention.

[0020] The principles resulting in such an increase of the deflectionangle are illustrated in FIG. 2, using a spherical model. The conditionspresent in the standard Hall-effect element according to FIG. 1 areindicated on the left side of FIG. 2. In this case, charge carriers 30move on a plane 52. The straight arrow in the left part of FIG. 2indicates first movement direction 31 of charge carrier 30 and isaccordingly denoted by reference numeral 31. Second movement direction32 corresponds to the movement direction of charge carrier 30 when amagnetic field is “switched on”. The deflection of charge carrier 30into second movement direction 32 produces the Hall voltage, which isknown in the standard Hall-effect element and acts in opposition to thedeflection direction or the deflection angle. This is represented in theleft part of FIG. 2, in that plane 52 perspectively “ascends to theright”. Therefore, charge carriers 30 deflected to the right into secondmovement direction 32 must even “run up” against the Hall-effectvoltage. The conditions according to the present invention arerepresented on the right side of FIG. 2. According to the presentinvention, charge carriers 30 no longer move on plane 52, but on a“convex potential-hill structure”, which is designated by referencenumeral 54. Due to structure 54, charge carriers 30 are more sharplydeflected from their first movement direction 31 (with the magneticfield “switched off”) and, indeed, into a third movement direction 33,which is represented by an arrow provided with reference numeral 33.Thus, the present invention provides for charge carriers 30 to be actedon by an additional lateral force, as soon as they are laterallydeflected from central flight path 31 by a magnetic field. The action ofthis lateral force intensifies the deflection effect of the“switched-on” magnetic field not shown in FIG. 2. The action of such alaterally increasing force may be implemented quite advantageously invarious ways in a real semiconductor element:

[0021] using lateral electric fields,

[0022] using lateral particle gradients,

[0023] using lateral diffusion profiles,

[0024] by modulating the band edges, or

[0025] by modulating the Fermi level in the local space,

[0026] e.g., using built-in potential hills in so-called nipistructures. In this case, the designation “lateral” refers to the xdirection represented in FIG. 1, i.e. to the direction in the drawingplane perpendicular to first movement direction 31 of charge carriers30.

[0027] Shown in FIG. 3 is the effect of a laterally increasing force onthe charge-carrier movement when the magnetic field is switched on, i.e.when B component 12 does not disappear. Region 20, which is particularlyprovided in the form of a region in a semiconductor set-up, is providedagain. In addition, first terminal 21 and second terminal 22 areprovided again, the first terminal being provided as, e.g. a negativeterminal 21, and second terminal 22 being provided, e.g. as a positiveterminal. However, first and second terminals 21, 22 are not providedalong the entire extension in the x direction of region 20, but areessentially provided in the center. A first electrode 23 and a secondelectrode 24 are provided directly on the sides of region 20. Both firstelectrode 23 and second electrode 24 are provided, for example, aspositive electrodes 23, 24. Set-up 10 is again represented in FIG. 3,but this time, in accordance with a first specific embodiment of thepresent invention. Inside region 20, in the lateral direction, i.e. inthe x direction, a field distribution 50 of a first electric field alongthe x direction is shown in the lower area of FIG. 3. Field distribution50 indicates the magnitude of the components in the x direction of thefirst electric field. The first electric field is not explicitly shownin FIG. 3. It is apparent that, starting out from the center of region20, the magnitude of the x component of the first electric fieldlaterally increases, i.e. both in the positive and negative xdirections. This means that, initially, as soon as the switching-on of Bcomponent 12 of the magnetic field to be measured causes charge carrier30 to no longer move along first movement direction 31 from firstterminal 21 to second terminal 22, but laterally deflects it into secondmovement direction 32, so that deflection angle 34 is formed, at leastin the beginning, and that the lateral deflection due to fielddistribution 50 causes charge carrier 30 to experience an additionallateral force. A cycloidal path of charge carrier 30, which is denotedby reference numeral 35, and whose deflection into third movementdirection 33 from FIG. 2 is sharper than second movement direction 32 inFIG. 3, is formed in that the additional lateral force in the xdirection produced by field distribution 50 causes charge carrier 30 tobe deflected further than according to second movement direction 32; thepartial cycloidal path ballistically traced by charge carrier 30 duringeach additional path part after a collision with the crystal latticebeing more sharply inclined than the previous partial cycloidal path,because, in addition to the magnetic-field effect of the Lorenz force,the potential hill structure built into region 20 and represented byfield distribution 50 also exerts a lateral force in the same direction.In this manner, charge carrier 30 is deflected a little more to theside, where the lateral force becomes stronger again, since themagnitude of field distribution 50 monotonically increases in thelaterally outward direction, and so on. In this manner, each additional,partial cycloidal path slopes more to the side, so that the deflectionangle of the flight path becomes greater and greater. The effect of Bcomponent 12, which, itself, always induces only a very small angularchange per partial cycloidal path, is drastically intensified by theeffect of field distribution 50. Therefore, very high deflection anglesconsiderably greater than 1° are, on the whole, attainable, thesedeflection angles amounting to several times the deflection of customaryHall-effect sensors.

[0028] First terminal 21 provided on the upper side of region 20 andsecond terminal 22 provided on the lower side of region 20 generate asecond electric field, which is also not shown and is provided in adirection essentially parallel to the introduction direction of chargecarrier 30 into region 20.

[0029] The first specific embodiment of device 10 according to thepresent invention, which is described in FIG. 3, is particularlyadvantageous for highly sensitive magnetic-field sensors, since theamplification effect of the lateral deflection of charge carriers 30also allows very small magnetic fields 12 to produce a sufficientlylarge, macroscopically measurable deflection.

[0030] The essence of the present invention is based on the applicationof the principle of lateral deflection-angle amplification, using asuitable potential-hill structure. The manner of detecting deflectedcharge carriers 30 may be implemented very advantageously in differentways. In particular, the described amplification principle is applicableto both lateral and vertical components. The described, lateralpotential-hill structure may be implemented in both vertical components,i.e. the central, main current flow occurs from the front side of thechip to the back side of the chip and such an element is sensitive tomagnetic fields oriented in a direction parallel to the upper chipsurface, and lateral components, i.e. the central, main current flow isprovided in a direction parallel to the upper chip surface and issensitive to magnetic fields 12 oriented perpendicularly to the upperchip surface. The choice of whether a vertical or a lateral component ispreferred must be made as a function of the application and the favoredcurrent flow and favored orientation of the magnetic field to bemeasured.

[0031] The options of the present invention for contacting andevaluating are correspondingly diverse. A first specific embodiment isalready represented in FIG. 3, where a current change or voltage changemay be measured through the lateral contacts, while the primary currentflows perpendicularly between terminals 21, 22.

[0032]FIG. 4 shows a second specific embodiment of device 10 accordingto the present invention. Identical designations from preceding figurescorrespond to the same parts, components, or directions. Once again,first terminal 21 is provided above region 20, essentially in the centerin the x direction, while second terminal 22 is provided in the centerof the lower side of region 20. In the second specific embodiment of thedevice according to the present invention, electrodes 23 und 24 areprovided on the lower side as well, but to the side of second terminal22. Located between them is a voltage-measuring instrument 45, whichallows the measuring signal of device 10 according to the presentinvention to be tapped off. Also provided in FIG. 4 is a first currentpath 41, which is essentially the only one used by charge carriers 30not shown, which arrive in region 20 from first terminal 21 when Bcomponent 12 is absent or disappears. In addition, a second current path42 from first terminal 21 to first electrode 32 is represented by adotted line on the left side of region 20. When B component 12 isswitched on, second current path 42 is preferably taken by chargecarriers entering region 20 from first terminal 21, since such chargecarriers 30, which, as was mentioned, are not shown in FIG. 4, follow afirst trajectory 35 resulting from the deflection effect of B component12, when the charge carriers from first terminal 21 enter region 20exactly in the center. According to FIG. 4, a charge carrier 30, whichis laterally displaced to the right as it enters region 20 from firstterminal 21, is moved, e.g. according to a further trajectory 36. In theexample shown in FIG. 4, a third current path 43 will have a lowernumber of charge carriers when B component 12 is switched on, since evencharge carriers provided for moving in accordance with second currentpath 42, due to their entry into region 20 from first terminal 21, donot move on this trajectory, but rather, for example, in accordance withsecond trajectory 36. This asymmetry between second current path 42 andthird current path 43 results in a potential difference between firstelectrode 23 and second electrode 24, which may be detected with the aidof measuring device 45.

[0033]FIG. 5 shows a third specific embodiment of device 10 according tothe present invention. Identical reference numerals from previousfigures denote the same components and directions of the describedobjects. Provided once again is region 20, which has first terminal 21on its upper side and second terminal 22 on its lower side, firstcurrent path 41 running between the first terminal and the secondterminal. However, in contrast to FIG. 4, i.e. the second specificembodiment of device 10 according to the present invention, electrodes23, 24 are provided on the upper side of region 20, laterally adjacentto first terminal 21. Therefore, second current path 42 and thirdcurrent path 43 are more sharply curved than in FIG. 4, and indeed, thecurrent direction in FIG. 5 is even reversed within region 20. A firsttrajectory 35 and a second trajectory are again shown by way of example.

[0034] Represented in FIG. 6 is a fourth exemplary embodiment of device10 according to the present invention, the fourth exemplary embodimentessentially matching the third exemplary embodiment from FIG. 5. Theonly difference is that, on the upper side of region 20, shieldingregions 26, 27 are provided between first terminal 21 and each laterallysituated electrode 23, 24 in such a manner, that a first shieldingregion 26 is provided between first terminal 21 and first electrode 23,and a second shielding region 27 is provided between first terminal 21and second electrode 24. Shielding regions 26, 27 may be provided asdiffusion regions, e.g. p-doped regions, when region 20 is n-doped;reverse-biased shielding regions 26, 27 suppressing a lateral surfacecurrent. However, the shielding may also be realized in the form ofetched trench structures, or by implantation. In addition, there is theoption of suppressing the surface current in the area of shieldingregions 26, 27, using a repelling electric current. In a manneranalogous to the formation of a conductive channel in a MOS transistor,where a conductive channel is formed below the gate electrode with theaid of a suitable voltage, one may analogously effect the opposite: Avoltage, which repels charge carriers (e.g. negative for the flow ofelectrons) and is at a gate electrode provided above the shieldingregions, suppresses the lateral surface current and forces the chargecarriers to flow in the depth of region 20, where they utilize the Halleffect in a considerably more efficient manner than on the chip topside,which is markedly deteriorated by surface imperfections. Shieldingregions 26, 27 cause reactive currents 46, 47 to be suppressed, a firstreactive current 46 flowing between first terminal 21 and firstelectrode 23, directly on the upper surface of region 20, and a secondreactive current 47 flowing on the upper surface of region 20, directlyfrom first terminal 21 to second electrode 24. Otherwise, identicalreference numerals are again used in FIG. 6 for the same components andorientations from previous figures.

[0035] In summary, the present invention generally relates to devices 10for measuring a B component 12, the effect of B component 12 beingintensified by the force action of a potential-hill structure, whichfirst of all runs laterally with respect to the undisturbed movementdirection (first movement direction 31), and which has, on the otherhand, an increasing force action with increasing distance in front ofthe undisturbed flight path of first movement direction 31 itself, theundisturbed flight path of the first movement direction being, ingeneral, centrally situated with respect to region 20. The cause of thisforce action may be both a drift movement, e.g. caused by electricfields, through built-in potentials, or through gradients of the Fermilevel, or also a diffusion movement, e.g. through particle-thickgradients, diffusion profiles, and the like, or a combination of a driftmovement and a diffusion movement.

[0036] Such components increasing the deflection angle, i.e. devices 10of the present invention, for measuring a B component 12, may beproduced in different processes. For example, bipolar, CMOS, or BCDprocesses are advantageous. In particular, it is advantageous that, inthe latter processes, the option of on-chip integration of the sensorelement is provided together with the triggering logic circuits andevaluating logic circuits, e.g. in the form of an ASIC.

[0037] On the basis of the device according to the present invention, itis possible to produce, in particular, highly sensitive magnetic-fieldsensors and ammeters, which are based on the measurement of the magneticfield of the current to be measured. In this connection, the use of suchmagnetic-field sensors and ammeters is particularly intended to be inmotor vehicles.

[0038] The present invention also provides for set-ups, such asrotation-rate sensors (yaw-rate sensors), angle-of-rotation sensors, andtorque sensors based on magnetic-field measurement to be equipped with adevice according to the present invention or a magnetic-field sensoraccording to the present invention. With the aid of the device or themagnetic-field sensor, such a set-up then measures a mechanicalmovement, using the change in a magnetic field, the mechanical movementbeing revealed, for example, by the change in position of a permanentmagnet due to the mechanical movement. This allows the rotationalmovement, the angle of rotation, the angular frequency, or the torqueof, e.g. an engine, a steering column, a steering wheel, or the like tobe detected, using the change in the magnetic field, that is, e.g. usinga change in the angle of the B-field vector of the permanent magnet atthe location of the sensor.

What is claimed is:
 1. A device (10) for measuring a B component (12) ofa magnetic field, the device (10) having a region (20), a charge carrier(30) being introducible at an introduction point (21), in anintroduction direction (31), the charge carrier (30) initially movingessentially along the introduction direction (31), the introductiondirection (31) being perpendicular to the B component (12), and theintroduction point (21) being essentially in the center of the region(20), wherein a field distribution (50) of a first electric field isprovided in the region (20) in such a manner that, in an x directionwhich is essentially perpendicular to both the B component (12) and theintroduction direction (31), the absolute value of the x component ofthe first electric field monotonically increases from the introductionpoint (21) in the x direction.
 2. The device as recited in claim 1,wherein a first electrode (23) and a second electrode (24) are providedadjacent to the region (20), the first and second electrodes (23, 24)being provided on both sides of the introduction point (21), in the xdirection.
 3. The device as recited in claim 1 or 2, wherein a firstterminal (21) and a second terminal (22) being provided, the first orthe second terminal (21, 22) being provided as an introduction point, asecond electric field essentially parallel to the introduction direction(31) being provided in the region (20) between the first and secondterminals (21, 22), and the charge carriers (30) being introducible intothe region (20) by the second electric field.
 4. The device as recitedin one of claims 1, 2, or 3, wherein the field distribution (50) isproduced by a lateral electric field.
 5. The device as recited in one ofclaims 1, 2, or 3, wherein the field distribution (50) is produced bylateral particle gradients.
 6. The device as recited in one of claims 1,2, or 3, wherein the field distribution (50) is produced by a lateraldoping profile.
 7. The device as recited in one of claims 1, 2, or 3,wherein the field distribution (50) is produced by modulating the bandedges or modulating the Fermi level in local space, in particular withthe aid of built-in potential hills in nipi structures.
 8. Amagnetic-field sensor having a device for measuring a B component (12)of a magnetic field as recited in one of claims 1 through 7, wherein themagnetic-field sensor includes an evaluation circuit for evaluating thesignals of the device (10).
 9. The magnetic-field sensor as recited inclaim 8, wherein the device (10) and the evaluation circuit aremonolithically integrated on a semiconductor substrate.
 10. An ammeteror set-up having a device (10) as recited in one of claims 1 through 7,or having a magnetic-field sensor as recited in one of claims 8 or 9.